JP-H08-258529A discloses an arrangement with a plurality of phase compensation filter means, one of which is selected depending on a resonance frequency of a sprung portion. Specifically, when the resonance frequency is high, one of the filter means which has a characteristic of small phase delay is selected. When the resonance frequency is low, one of the filter means which has a characteristic of large phase delay is selected. In this arrangement, when a load applied to the sprung portion is small and accordingly the resonance frequency is high, it is possible to improve responsiveness and satisfactorily obtain a vibration suppressing effect, by selecting the filter means having the characteristic of small phase delay. JP-H05-319056A discloses an arrangement with phase delaying means and phase advancing means, one of which is selected depending on a frequency of a sprung portion. Specifically, the phase advancing means is selected when the frequency is not lower than a predetermined value, and the phase delaying means is selected when the frequency is lower than the predetermined value, whereby a ride comfort is improved by this arrangement. JP-H07-89321A discloses an arrangement for controlling, based on absolute velocities of respective sprung and unsprung portions, a vertical force generator that is disposed between the sprung and unsprung portions in parallel with a suspension spring and a shock absorber. Specifically, a gain used for the control based on the velocity of the sprung portion and a gain used for the control based on the velocity of the unsprung portion are determined by taking account of a load received by the suspension spring and the shock absorber. Each of JP-H07-32838A, JP-H05-201224A and JP-H03-16281B2 discloses an arrangement for controlling damping characteristics based on, for example, vibration of the sprung portion.